The goal of this project is to produce complete annotations (transcriptions) of previously collected longitudinal samples of the development of American Sign Language (ASL) by preschool aged Deaf children; to analyze these data at the lexical, morphological, and syntactic levels to provide benchmarks of typical development; and to make both the annotated videos and linguistic analyses of each session available to researchers, teachers of the deaf, sign language teachers, and the sign language community. Deaf people are often primarily users of a sign language; in the US, this is ASL. While knowledge of English is also important, ASL may be the first and/or preferred language due to its accessibility. For this reason, accurate and detailed data on the development of ASL by Deaf children is an important resource. Professionals can use such information to assess language development in a variety of circumstances, both typical and atypical. The project requires two prongs of approach. On one side, improvements will be made to an existing platform for annotation of video data. In particular, to make this platform optimal for sign language corpora, a system for integrating a sign language lexicon database is required. On the other side, annotators will use this system to standardize and finalize an existing partially-completed set of transcripts covering over 200 hours of video-recorded interactions between Deaf children and their Deaf parents or other interlocutors. These data will be analyzed at three levels of linguisti structure. In particular, the analysis will focus on areas of language which are known to develop during the age range observed. In conducting this analysis, the project will reveal paths of language development that are particular to sign languages, as well as ways that sign language development and spoken language development coincide. In the end, the video data, annotations, and linguistic coding will all be made available using web-based archiving systems. This is the first time that such a resource will be shared with the sign language acquisition community.